Abstract: Opioid receptors have been targeted for the treatment of pain and related conditions for thousands of years. Three opioid receptors have been characterized, with a fourth opioid receptor called nociceptin (NOPR) or opioid-receptor like-1 being the newest member of the family. Recent evidence has shown that opioid receptors are potentially novel targets for addiction, anxiety, and depression. Furthermore, reports suggest that the NOPR - nociceptin system is involved in cocaine reward behavior. However, where in the brain NOPR receptors modulate these behaviors, how NOPR is regulated, and how it signals has not been defined. In order to better understand the role of this system in behavior we propose 2 aims: 1) We will determine how NOPR and NOPR -signaling mutants function in specific cells and dopaminergic neural circuits to control cocaine preference behavior using targeted viral rescue strategies, and behavioral models. Here we will employ viral-mediated cell type specific knock-in gain-of-function experiments in mice, using wild-type and mutant receptors to determine how NOPR receptors function in dopaminergergic circuits to control cocaine preference in vivo. 2) In aim 2 we will use a combination of mouse genetics, anatomical techniques with tDtomato-reporter mice, and optogenetic approaches to dissect the role of nociceptin containing neurons on cocaine place preference, reward, and aversion behavior. Together, this project and the experiments described could provide novel and important information about nociceptin-NOPR system function in drug abuse behaviors.